Circulating air ovens for drying and/or fusing, in short, for treating, material webs, especially textile material webs, guided through the oven comprise a housing, in which transport means for guiding a material web through the housing are arranged. Nozzle chambers, which are arranged one next to the other and parallel to the transport direction, are attached above and below the transport means. Nozzles are attached to opposing side surfaces of these nozzle chambers facing the transport means. With the nozzles, air is blown onto the material web. The nozzle chambers are arranged in a closed discharge chamber, from which the air emerging from the nozzles is suctioned and—heated and compressed—fed back to a pressure chamber, in order to be blown again through the nozzles onto the material web.
The circulating air dryer known from EP-A1 148 113, which is built in the way described above, has the disadvantage that the air blown onto the material web is fed to the material web in a well controlled manner, but flows away from there in an uncontrollable manner, because there are not consistent relationships in terms of the surface quality, density, and thickness of the material web, and also the distance between the pressure housings.
Furthermore, from DE-A1 3130297, a device for heat treatment of a continuous web is known, in which a channel with high pressure and a channel with low pressure are allocated to each nozzle chamber. Flaps on the channels permit air to be blown with the nozzles onto the continuous web on both sides or to be suctioned from there or to be suctioned from one side and to be blown onto the other side. In addition, the nozzle chambers lie side to side, so that the blown air is suctioned through an adjacent housing or through an opposing chamber. A disadvantage for this device is that an alternating flow of air through the continuous web from bottom to top and from top to bottom is not possible.
In this respect, the invention seeks to provide a solution. Therefore, the objective of the present invention is to create a circulating air oven, which permits a controlled flow of process air to and from the material web according to essentially freely selectable criteria.